1. Field of the Invention
The present invention relates to an optical element having a birefringence functional layer. More specifically, the present invention relates to an optical element having a birefringence functional layer including a birefringence layer obtained by orienting and fixing a liquid crystal molecule, a member for a liquid crystal display device using the optical element, and liquid crystal display device.
2. Description of the Related Art
A liquid crystal display device has found use in a variety of fields such as a television and medical equipment because the device has such advantages that the thickness and the weight of the device can be readily reduced, power consumption can be reduced, and a flicker hardly occurs. On the other hand, the device involves a problem which causes light leak or a tone reversal phenomenon depending on the angle at which a user views a liquid crystal display screen, that is, a problem referred to as a narrow viewing angle.
In order to solve the problem, there has been proposed a liquid crystal display device provided with an optical element that controls an outgoing light emitted from a liquid crystal cell and an incident light entered into the liquid crystal cell.
For such the liquid crystal display device, there has been proposed an optical element having a film obtained by orienting and fixing a liquid crystal molecule in a specific direction as well as a film obtained by subjecting a triacetylcellulose (TAC) film to uniaxial stretching or biaxial stretching.
JP 05-142531 A proposes a viewing angle compensation film composed of a nematic liquid crystal polymer whose molecular chain is oriented in a normal direction of the film surface and which has a positive intrinsic refractive index. JP05-142531 A discloses that the viewing angle compensation film may be obtained by: forming a vertical alignment layer on the surface of a glass substrate or the like by using an alkylsilicone-based or fluoroalkylsilicone-based surface treating agent to produce a cell; sealing liquid crystal molecules into the cell; and subjecting the liquid crystal molecules to photopolymerization.
JP2002-174724 A proposes a method of producing a liquid crystal layer in which a polymerizable liquid crystal compound is homeotropically oriented, the method involving applying the liquid crystal compound to a vertical alignment layer formed on a substrate. The method involves the use of a long-chain alkyl-type dendrimer derivative as an agent for forming a vertical alignment layer. In addition, JP 2002-174724 A discloses that a film including a homeotropically oriented liquid crystal film can be obtained by means of the method, and that the film can be used for an optical film such as a retardation film.
JP 2002-174725 A proposes a method of producing a homeotropically oriented liquid crystal film involving: applying, to a substrate provided with no vertical alignment layer, a side-chain type liquid crystal polymer containing a monomer unit containing a liquid crystal fragment side chain and a monomer unit containing a non-liquid crystal fragment side chain; further homeotropically orienting the liquid crystal polymer in a liquid crystal state; and fixing the polymer while the oriented state is maintained.
JP 2003-121852 A proposes a method of producing a homeotropically oriented liquid crystal film involving: forming, on a substrate provided with no vertical alignment layer, a binder layer and an anchor coat layer in the stated order from the side of the substrate; applying a side-chain type liquid crystal polymer to the anchor coat layer for homeotropic orientation; and fixing the polymer while the homeotropically oriented state is maintained. The method involves the use of a polymer as a side-chain type liquid crystal polymer capable of forming a homeotropically oriented liquid crystal layer on a substrate provided with no vertical alignment layer.